Multichannel bioelectronic sensing using engineered Escherichia coli

Abstract

By engineering extracellular electron transfer (EET) to be dependent on an analyte, researchers have developed whole cell bioelectronic sensors that sense hazards to human and environmental health1. However, these sensors regulate a single electron transfer pathway as an electrochemical channel, limiting the sensing information to a single analyte. To increase information content, we developed a multichannel bioelectronic sensor through which different chemicals regulate distinct extracellular electron transfer pathways within a single Escherichia coli cell. One channel utilizes the flavin synthesis pathway from Bacillus subtilis2 and the other a set of cytochromes constructing the Mtr pathway from Shewanella oneidensis3. We demonstrate an arsenite responsive promoter can control the Mtr pathway through activation of cytochrome CymA expression and a cadmium responsive promoter can control the flavin synthesis pathway4,5. The redox potential of flavin-mediated EET is different from that of CymA-mediated one6. This allowed for development of a redox-potential-dependent algorithm that distinguishes variable input signals of each analyte mediated by two EET pathways in vivo. This approach enables a 2-bit binary signal readout for real-time tracking throughout the entire sensing duration. Our multichannel bioelectronic sensor was able to accurately sense and distinguish different heavy metals in Brays Bayou water samples with a response time comparable to that in clean water. This multichannel bioelectronic sensors allow for simultaneous detection of different chemicals, significantly expanding information transmission and helping to safeguard human and environmental health.